JPS61151244A - Method for pretreating resin molding for coating - Google Patents

Abstract

PURPOSE:To remove a solvent remaining on the surface of a molding to prevent failure in plasma treatment, by washing a resin molding with a solvent vapor and treating it by hot air blowing, oven heating or high-pressure air blowing. CONSTITUTION:A resin molding 8 to be treated is held by a holding device 8 and transferred to a solvent vapor washing chamber 1 to be washed with the vapor of a solvent 3 evaporated by heating it in a heater 4. The washed material to be treated is introduced into a high-pressure air or hot air treating chamber 2 and blown by air or hot air introduced through an air or hot air introducing pipe 9 and fed from a blower 10, to thereby remove the solvent remaining on the surface of the material 8 to be treated. In this way, the solvent remaining on the surface of the material 8 to be treated can be removed in a short time and the subsequent evaporation rate of the solvent is very slow and hence failure plasma treatment due to the evaporation of the solvent in a plasma chamber can be prevented.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention is a method for pre-painting a resin molded article, in which plasma treatment is performed after solvent treatment. Regarding how to remove.

[Conventional technology and its problems]

In order to improve the paintability of resin molded products, particularly polyolefin resin molded products that have poor paintability, pretreatment with low-temperature plasma is generally performed.

On the other hand, the surface of resin molded products is dirty due to dirt from the mold, adhesion of anti-rust oil to the surface, or the absorption of dust due to its own static electricity, which makes it difficult to maintain a high-quality painted appearance. To achieve this, it is necessary to degrease and clean before plasma treatment. There are several methods for this method, but the solvent vapor cleaning method is superior (Japanese Patent Application Laid-Open No. 57-158
(See Publication No. 70).

However, depending on the length of time left until plasma treatment is performed after solvent vapor cleaning, plasma treatment defects may occur. That is, especially in a type of plasma processing apparatus in which a reactive gas is turned into plasma outside the plasma processing chamber and introduced into the processing chamber, the solvent remaining on the surface of the resin molded product evaporates and diffuses into the plasma processing chamber. This is thought to be because the steam deactivates the paintability improving components (reactive gas radicals) in the plasma-formed gas before reaching the surface to be treated, thereby inhibiting the plasma treatment.

Further, solvent vapor is not preferable because it accelerates deterioration of the O-ring, gasket, sealant, oil of the oil rotary pump, etc. in the plasma processing apparatus.

In order to prevent the generation of solvent vapor in the plasma processing chamber, it is possible to leave the product for a longer time after solvent vapor cleaning and before plasma processing, but this has the following drawbacks in terms of productivity and quality on mass production lines. .

1. A place is required to store resin molded products after solvent vapor cleaning.

2. If you leave something that has been degreased and cleaned, it will pick up dirt such as flakes and become dirty again, so a device is needed to prevent this.

5. It is necessary to control the time the bath agent is left for after steam cleaning.

4. If plasma treatment is performed continuously even after being left for a long time, the plasma treatment chamber will accumulate solvent and will need to be left for a long time.

[Structure of the invention]

The present invention provides a method for pre-painting a resin molded article in which plasma treatment is performed after solvent vapor cleaning, in which (
1) Hot air blowing, (2) heating in an oven, and (3)
This is a pre-painting method for a resin molded article, characterized in that one or more treatments selected from the process consisting of high-pressure air blowing are performed to completely remove the solvent remaining on the surface of the resin molded article.

The present inventor conducted various studies to solve the above-mentioned problems when performing plasma treatment after solvent vapor cleaning as a pre-painting treatment for resin molded articles, and as a result, the present invention vi'' was completed.

That is, as mentioned earlier, when performing plasma treatment after solvent vapor cleaning, it was thought that the reason for plasma processing failure was due to the solvent vapor generated in the plasma processing chamber, so in order to confirm this, 1g1 .1-) Lichloroethane (liquid temperature set at 80°C: Actual liquid temperature is 74°C or less)
After performing steam cleaning for 20 seconds, a paint adhesion test was conducted under the following conditions using the standing time until plasma treatment as a parameter, and the results shown in Table 1 were obtained.

Plasma chamber internal volume: approx. &4m2 High frequency: 2450 MFiz Reaction gas: 02. Flow rate: 1.3 t/min After plasma treatment was performed under the conditions of a treatment room pressure of 8 Torr or more, paint R-256 manufactured by Nippon Bee Chemical Co., Ltd. was applied and hardened by baking at 90° C. for 50 minutes.

Table 1 × Standing time includes the time until the plasma processing chamber is evacuated.

Next, use the same material as used in the test: 50X 5
An injection molded article measuring 0.times.2 m was washed with solvent vapor in the same manner as described above, and after being left at room temperature, the weight of the molded article was measured to determine the amount of solvent remaining on the surface of the molded article. The results are shown in Table 2 below.

As can be seen from the results shown in Table 2, it can be seen that when the standing time after solvent vapor cleaning is short, a considerable amount of solvent remains on the molded product.

From the results shown in Table 1 and Shishi-2, it is understood that if the standing time between solvent vapor cleaning and plasma processing is short, a large amount of solvent vapor will be generated in the plasma processing chamber, inhibiting plasma processing. There will be.

In addition, in cleaning by wiping with a solvent or immersion treatment in a solvent (at room temperature), almost no solvent remains on the resin surface after cleaning. In the case of solvent vapor cleaning, the high temperature solvent vapor swells the surface of the resin molded product and the solvent penetrates to a considerable depth on the resin surface, so it is thought that a large amount of solvent remains.

In order to solve the problems in plasma processing using residual solvent, the present inventor conducted a study and found that a resin molded product is heat-treated immediately after cleaning with solvent vapor or during the transportation process to a plasma processing apparatus. By blowing with hot air or high-pressure air, not only can the solvent remaining on the surface of the resin molded product be removed in a short time, but the subsequent evaporation rate of the solvent is extremely low. We have discovered that it is possible to prevent the occurrence of plasma processing defects due to the evaporation of the solvent in the goods machine chamber as a result of the delay, and have thus arrived at the present invention.

The conditions for each treatment are that when heat treatment and hot air treatment are carried out, it is sufficient to carry out the treatment at a temperature of several seconds or more at a temperature that does not deform the resin molded product, and in the case of high pressure air blowing, it is sufficient to carry out the treatment at a temperature of 1.2 kgf/c.
It is sufficient to blow for several seconds or more using air at a pressure of m'' or more.

In order to demonstrate the effects of the present invention, polypropylene (X-129
1.1.1-) An injection molded product of 50×50×311II++ manufactured by Mitsubishi Yuka Co., Ltd.
After steam cleaning for 0 seconds, perform the following A-F processing,
Changes in the amount of remaining solvent over time were determined. The results are shown in Table 3 and illustrated in FIG. 4.

From the results shown in Figure 4 and especially Figure 4, when using the method of the present invention (B, O, D, K), the residual solvent decreases rapidly and the subsequent solvent It can be seen that the evaporation rate is slow.

Next, based on the drawings, the BA model will be explained.

FIG. 1 is a schematic diagram showing an example in which a high-pressure air or hot air treatment chamber is provided above a solvent vapor cleaning chamber, where 1 is a solvent steam cleaning chamber, 2 is a high-pressure air or hot air treatment chamber, and 3 is a solvent vapor cleaning chamber. , 4
is a heater, 5 and 6 are cold water pipes, 7 is a workpiece holder, 8 is a workpiece, 9 is a hot air or air introduction pipe, 10 is a blower,
Reference numeral 11 indicates a processing object moving device V. Further, FIG. 2 shows a plan view of the processing apparatus shown in FIG. 1.

The workpiece 8 is moved to the moving device 11 while being held by the holder 7.
The solvent is first transported to a solvent vapor cleaning chamber 1, where it is cleaned by the solvent vapor generated from the solvent 3, which is heated to boiling temperature by a heater 4.

The evaporated solvent is cooled by a cold water pipe 5 provided at the upper part of the solvent cleaning chamber 1, condensed, and returned to the solvent 3.

The workpiece cleaned with the solvent vapor is then guided into the high-pressure chamber or hot air treatment chamber 2 in the upper part of the solvent vapor cleaning chamber, where the hot air or air is introduced through the hot air or air introduction pipe 9 and blown by the blower 10. Alternatively, the solvent remaining on the object 8 to be treated is removed by blowing with air. The solvent generated in the processing chamber 2 is F-cooled and condensed in a cold water pipe 5 provided above the processing chamber 2, and is returned into the solvent 5.

Figure 3 shows solvent vapor cleaning chamber 1 and residual solvent removal chamber (heating chamber)
This shows an example in which the heating chamber 12 is provided separately;
Reference numeral 6 indicates a 710 heating device, 14 indicates a heat insulating material, and other symbols have the same meanings as those shown in FIG.

In the apparatus shown in FIG. 3, the workpiece 8 cleaned in the solvent vapor cleaning chamber 1 is equipped with a heating device at the bottom, and a heat insulating material 14
transferred to a heating chamber 12 surrounded by and heated in the chamber,
Residual solvent is removed. The solvent evaporated in the heating chamber 12 is cooled and condensed by the cooling water pipe 6, and after being recovered as a solvent (not shown), it is returned to the solvent vapor cleaning chamber.

Note that it is possible to use a high pressure air or hot air treatment chamber instead of the heating chamber, and in this case, the heat insulating material may be omitted.

Heating equipment or hot air blowing or high pressure air blowing equipment:
It may be provided independently of the solvent cleaning device and between the solvent cleaning device and the plasma processing chamber.

In this case, the paint baking dryer may be used as a heating device, or a normal heating device or a heating device using infrared rays or the like may be provided separately.

Further, the heated air in the paint baking drying device may be used as the hot air source of the hot air blowing device.

In any case, it is preferable to provide a forced exhaust device and a cooling device in the exhaust section to prevent evaporated solvent from leaking outside.

Example Polypropylene
After steam cleaning for minutes (liquid temperature 70°C or higher), A: left in a 501% RH room at 23°C for 15 minutes, and measured the remaining amount of 1.1.1-)lichloroethane on each plate. A 27f/m" B 7f/m" 0 22f/m" and fc, respectively.

Next, the flat plate that has undergone the above treatments A, B, and O is BRA
NSOll IPO 30D 5-1102D
8TQJRAUTOMAT OPLASMA SYS
Plasma treatment was performed using TEM under the following conditions.

Reaction gas o2 Reaction pressure 1.0 Torr High frequency IN56MH2 High frequency output 200W Purge gas N2 Treatment time 30 seconds Next, paint R-263 (Nippon B Chemical Co., Ltd.) was applied to a thickness of approximately 50 μm on each plasma-treated plate, and the temperature was 90°C.
After baking for 40 minutes and leaving it indoors for 72 hours,
When the beer peel strength in the 180° direction of a coating film with a width of m1 was measured, A: 1. O0kpf/cm B: 1.38 to 9f/l:m O: 1.26kgf 7cm.

As can be seen from this result, when using the method of the present invention,
The adhesion of the coating film is significantly improved.

[Brief explanation of drawings]

Figure 1 is a side view of an apparatus for implementing the present invention, Figure 2 is a plan view thereof, Figure 3 is a side view of another apparatus, and Figure 4 shows changes over time in the amount of solvent remaining on the polypropylene surface. FIG.

Claims (1)

[Claims] 1. In a pre-painting treatment method for a resin molded article that is subjected to plasma treatment after solvent vapor cleaning, the process selected from the following steps is performed before plasma treatment: (1) hot air blowing, (2) heating in an oven, and (3) high-pressure air blowing. Or, a method for pre-painting a resin molded article, which comprises performing two or more treatments to remove the solvent remaining on the surface of the resin molded article.